Japanese Patent Application Publication No. 2005-116963 discloses a switching device having a semiconductor substrate, an upper surface of which is connected to a heat sink block by soldering.
Further Japanese Patent Application Publication No. 2011-187708 discloses a switching device having a plurality of trenches that extend linearly in an upper surface of a semiconductor substrate. Each of the trenches extends parallel to one another along a certain direction. Inner surfaces of the trenches are covered with gate insulating films. Gate electrodes are disposed inside of the trenches. An interlayer insulating film covers an upper surface of the semiconductor substrate and the gate electrodes. A contact hole is provided in the interlayer insulating film above each semiconductor region (hereinafter referred to as an inter-trench region) interposed between each pair of adjacent trenches in the semiconductor substrate. An upper electrode covers the interlayer insulating film, and is in contact with the semiconductor substrate in the contact holes. Each of the inter-trench regions includes a first region (emitter region) of a first conductivity type (n-type), and a body region of a second conductivity type (p-type). Each of the first regions is in contact with the upper electrode and the corresponding gate insulating film. The body region is in contact with the upper electrode, and is in contact with the gate insulating films below the first regions. Further, the semiconductor substrate includes a second region (drift region) of the first conductivity type. The second region is in contact with the gate insulating films below the body region, and is separated from the first regions by the body region. In this switching device, when a potential of the gate electrodes is controlled to a predetermined potential, channels are formed in the body region. The first regions and the second region are electrically connected by the channels. Accordingly, a current flows between the first regions and the second region.